Enhancing Seismic and Resilient Performance of Resilient Walls with Concealed Bracings: Experimental and Numerical Investigation

Abstract Resilient walls incorporating ultra-high-strength bars (UHSB) with weak bond performance are expected to exhibit drift-hardening properties. Thus, to improve the shear stiffness and lateral resistance of the resilient walls, the present research applied the concealed bracings composed of UHSB to the resilient walls and explored the effect on the hysteretic and resilient performance of the proposed walls. Five walls were tested to investigate the effect of relevant variables, including shear span ratio, the presence of steel fibers and recycled aggregate concrete (RAC) strength, on the hysteretic performance and resilience. Reinforced with bracings, test wall showed satisfactory hysteretic and resilient performance up to 2% drift ratio and maintained stable increase in lateral force. Concealed bracings consisted of UHSB were also conducive to reducing residual drift ratio, ranging from 8.7–31.3%. Residual drift ratios of all test walls were within the limit value of 0.5%, until a loading drift ratio of 2%. Additionally, adding steel fibers restricted the development of cracks and had a positive effect on slowing down stiffness degradation. Numerical models were established based on OpenSees platform, and more resilient-related parameters were analyzed, including reinforcement ratio and arrangement height of the concealed bracing ratio, longitudinal reinforcement ratio, axial ratio, and UHSB replacement ratio. Based on the parameter analysis results, design recommendations were given.